Fix build.

Add Constant opt/telephony project was requiring.  I suspect there is a change
coming that will add this and perhaps more, but this fixes the build.

Change-Id: I8f994c0cf9ed37f14dc7ae9368da07fe8cd76aec

telephony/java/com/android/internal/telephony/DctConstants.java

@@ -98,6 +98,7 @@ public class DctConstants {
     public static final int CMD_IS_PROVISIONING_APN = BASE + 38;
     public static final int EVENT_PROVISIONING_APN_ALARM = BASE + 39;
     public static final int CMD_NET_STAT_POLL = BASE + 40;
+    public static final int EVENT_DATA_RAT_CHANGED = BASE + 41;
 
     /***** Constants *****/